Hi,I am in northern california over the bay in oakland.what my question is.Since I live in a temperate zone where it does not freeze why have two deeps for the hive, why not a deep then the honey supers?

Generally a queen will lay in two boxes, unless forced to stay in one box by using a queen excluder. So even if you only use one deep, then other sizes, the queen will still want to lay more in the other boxes.If you keep her to one brood box, your hive won't grow as big. And sure, that's not a real problem to have only one brood box to go through winter if you live in a nice climate. But there are also less bees to collect honey for you. More bees means more work gets done.

In So Cal, I used to overwinter in a single deep. But I'm not sure you could call it overwintering. There were very few weeks that the bees didn't fly, and it was as much an equipment issue for me as it was a plan. I think your winter is quite a bit cooler than it was down in san berdo.

I'm in a very cold climate. I run NO deeps at all. I cut all of the ones I had down to mediums and that's all I buy. In fact NOW I'm only buying eight frame mediums.

Well to be PERFECTLY honest I still have two deeps with bees still in them because I haven't gotten the bees to move out yet. :)

If you run no excluder (and I don't) then why do you care where the brood leaves off and the supers start? It's just a matter of enough stores for the number of bees for your climate and if it never really gets cold you can always feed if you run short.

I'm not far from you, just south a bit in Santa Cruz. I have a deep and two mediums for my brood area because the queen is laying like crazy and needs just about that much room. She disn't need that much her first year but this year, her second, she is really needing that space. The deep and two mediums are what I left on for winter but at that time the two meds were full of honey. They didn't need that honey around here because we get the eucliptus flow in the winter and the bees feed off that. When I saw they didn't use all that honey I extracted it in February and put the boxes back for the bees to clean up. Then I got busy and didn't have time to take them off again but the queen started using it for brood so it's all okay.I did decide to put an excluder on and we'll see how that goes.